Ask ecologists what is the best measure of the health of an environment and they will tell you diversity. There are a multitude of ecological niches from the frozen tundra to boiling hot springs, from bone dry deserts to ocean expanses. In every case, greater biodiversity signals greater productivity and hence greater sustainability. Broader plant diversity means more food available to herbivores, and more herbivores makes for more prey animals.
Homo Sapiens, the only species on the planet that is actually capable of thinking about its impact, doesn’t. At least not much. We might forgive our Ice Age ancestors for wiping out most the megafauna on the planet because they didn’t realize their impact, but whenever humans showed up on the scene large animals disappeared. Other than Africa where we co-evolved with several large mammals, few are left around the world. Even the African species are dwindling.
The slaughter began as modern humans migrated out of Africa as early as 100,000 years ago. Europe, Asia, Australia and finally the Americas saw the rapid disappearance of large mammals. Some blame may be placed on changing climate, especially what is called the Holocene extinction at the end of the last glacial period, about 12,000 years ago. This period coincided with human migration into the Americas. Not only did the more northerly megafauna disappear but others such as a giant beaver as big as a compact car and a giant ground sloth which towered over 20 feet tall.
A similar rapid extinction took place when humans made their way to Australia about 40,000 years ago. A prehistoric marsupial weighing in at 3 tons disappeared shortly after human arrival. Also on the extinct list are a 2 ton Goanna (lizard), a turtle with a shell diameter of over 6 feet, and 500-pound flightless bird.
Probably the best-known example of a human-caused extinction is that of the Dodo, a 50 pound flightless relative of pigeons. Over a very short period of time it was extirpated from its island in the Indian Ocean. The Dodo was first seen by Dutch Sailors in 1598. It was gone from history by 1662, a species driven to extinction over the course of one human lifetime.
At the same time that we drive wild megafauna to extinction, we are replacing them with a very limited number of livestock, principally cattle, sheep, hogs and chickens and little else.
The combined mass of humanity is currently around 300 million tons, that of our livestock, 700 million tons. Compare that with the combined weight of everything from beavers to blue whales, which adds up to only 100 million tons. There are 200,000 wolves in the wild compared to 400 million dogs. Our closest relative the chimpanzee number about a quarter million compared to 7.6 billion of us.
The last western Black Rhino died in 2011, the last male Northern White Rhino died last month, leaving two infertile females of the species. Biodiversity means resilience means sustainability. What is our plan for our descendants?